Yes, it is done in ZX BASIC. The Water-Animation is slower than on C64, but C64 has a character-based display where if you change a font character, it is instantly updated on the entire screen. Spectrum has a bitmapped display, so the updates must be written everytime to all animated cells. But it the game is still excellently playable. Surely I could do it faster, but I think, the current speed is fully okay for a compiled ZX BASIC program and will cause some "Wow's!" on WOS . The Grow of Molusks (The invaders) is also slower than on C64, but this is a turn-based game.I hope to get the music within 1 week.

Go to the ZX Spectrum section of my homepage and click on the screenshoot. I hope you will like the game. For the sound effects I used BeepFX. 128K soundtrack was caned because the game uses all available ressources and this distrubed the interrupt routine too much.Here is the direct link: http://members.inode.at/838331/zx/Earthraid.zip

slenkar wrote:nice little game, I was able to do level 1 easily but maybe the others will offer more challenge

It is a almost 1:1 conversion from C64. The game plays exactly equal as on C64. The difference between levels is following:For each level the mollusks lifetime is increased by two rounds, you must wait two rounds longer for a missile and there is less water.Its not a question of winning, but the question of score.By the way, I noticed that BeepFX crashes in ZXBC if is called inside a SUB:

Outside subs it works fine.On C64 the game took 4 kb by the way, but coded in pure assembler, on hardware that has character based display and sprites and SID. I had to use many tricks to make the conversion working, and these use much memory. Anyway, I'm happy with this conversion.

I used Britlions Putchars and two counters for animation frames: one for water (8 frames) and one for mollusks (4 frames), then scanned the playfield. Everytime a water or mollusk was detected, the tile was redrawn with new frame of animation. There was also a sup which redraws on a mask, to not let the helicopter or missile flicker over mollusks or water, as Spectrum has no sprites. I also though about a possibility to use a second screen to eliminate any flickering and tearing, but I wanted to make the game playable on Spectrum 48K.So for the speed of graphics I credit Britlions PutChars routine.I hope to show with this game on WOS how fantastic ZXBC is, and get more users who will use it. And to demonstrate the speed of development I released two games at same time.